Zach Polonsky: "Nothing and Anything: $B\to X_s\nu\bar\nu$ in the Standard Model"

Thursday 19 Feb 2026, 13:30 → 15:00 Europe/Rome

Sala Direzione INFN

Flavor-changing neutral current (FCNC) decays are heavily suppressed in the Standard Model (SM), making them ideal processes to search for weakly-coupled beyond SM physics. Semi-leptonic decays are particularly convenient from the theoretical point of view, as they do not suffer from the same large uncertainties as fully hadronic decay modes. Furthermore, the neutrino modes are free from contamination from the poorly-understood long-distance physics which plagues the charged-lepton modes, making them highly theoretically clean decays in the SM. Measurements in recent years by the Belle II collaboration have indicated possible tensions between SM predictions and experiments in exclusive-mode $b\to s\nu\bar\nu$ decays, and have placed the first upper bounds on the inclusive decay, warranting further study on the theory side. The inclusive decay is especially interesting due to the fact that it is free from lattice form-factor uncertainties, instead being calculated using heavy quark effective theory, allowing for a highly precise, percent-level determination of the $B\to X_s\nu\bar\nu$ decay rate. In this talk, I will present the most up-to-date predictions for the total rate as well as the partial rates with kinematic cuts relevant to the Belle II experiment.